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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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CHAPTER
NUNATAK AND CASCADING GLACIERS
NONATAK GLACIER
General Description.1 As in the case of all the larger glaciers of this region the name was given by Russell. He saw this glacier in September, 1891, from Cape Enchantment, opposite the mouth of Nunatak Fiord and says2 that "near where it enters the bay it is divided by a rounded butte of bare rock that rises through it like an island and that suggested the name 'Nunatak Glacier.5" A nunatak in Greenland is a mountain peak rising above the glacier, which surrounds it, and Russell speaks of this in another publication8 as "a rounded dome of rock which rises through the ice and forms a nunatak." If the nunatak had this appearance in 1891 both of the tongues of the glacier must have extended much farther than they did in 1905; but from Russell's distant point of view he might well have thought the hill surrounded, even though the two tongues fell short of junction by a considerable amount. When mapped fiy the surveyors of the Canadian Boundary Commission, in 1895, the glacier terminated in two tongues, or distributaries, the northern and larger one ending in a sea cliff (Pis. LIX, LXVIII), the smaller, southern one on the land in a valley south of the nunatak. The glacier is still in this condition (Map 4, in pocket), though there has been material recession in each of the distributaries.
From the top of the nunatak one sees that at a distance of three or four miles from the sea two large tributaries unite to form the lower portion. The southern tributary heads upon a broad, flat, snow-covered divide, beyond which, according to the prospectors, the ice descends eastward toward the Alsek valley (PL LVIII). There is certainly an open valley without lofty mountains, in this direction. It is, therefore, a through glacier, and in 1898 it was traversed by prospectors as a highway to the Alsek. The Boundary Survey map indicates also a branch through a valley leading southward to the Hidden Glacier, but this is hidden from sight from the places where we obtained views of the glacier. We cannot tell whether the southern tributary of the Nunatak Glacier receives any notable tributaries, but the absence of medial moraine upon its surface indicates that there are no such tributaries. There is a well-defined lateral moraine on the south side, and another on the north side. The latter joins the south lateral moraine of the north arm and forms a prominent, medial moraine on the lower glacier below the junction of the two tributaries. That the southern arm receives no notable contributions from tributaries is also indicated by its weakness, for the northern arm pushes over into its territory; it is failing to continue to supply the land tongue of the glacier with ice, and
i See Tarr, R. S. and Martin, La-wrence, Glaciers and Gkciation of Yakutat Bay, Alaska, Btdl. Amer. Geog. Soc., Vol. XXXVm, 1906, pp. 149-150; Tarr, R. S., The Yakutat Bay Region, Alaska, Professional Paper 64, U. S. Geol. Survey, 1909, pp. 54-68.
113th Ann. Rept., U. S. Geol. Survey, pt. II, 1892, p. 86.
1 Glaciers of North America, Boston, 1897, p. 95.
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